Protective dial assembly for permutation locks



May 27, 1958 H. C. MILLER 2,836,052

PROTECTIVE DIAL ASSEMBLY FOR PERMUTATION LOCKS Filed Nov. 17. 1955 /5 mur umlmunuf//l f4 ZZ 74 30 INVENTOR Q7 f25 /ZV/fy'/V/ier ATTORNEYS United States Patent PROTECTIVE DIAL ASSE ratify' FOR PERMUTATIN LGCKS Harry C. Miller, Rochester, N, vApplication November 17, 1955, Serial No. 547,4@

5 Ciaims. (Ci. 7th-332) The present invention relates in general to permutation locks, and more particularly to a dial and dial ring assembly for permutation locks aiording security against detection by a distant observer of the combination used in Aopening the lock.

It has been long recognized that the combinations of permutation locks are subject to theft by unauthorized viewing of the successive registrations of the dial markings occurring during opening of the lock. Where such a lock is opened in the presence of other persons, it is a simple matter for such persons to note the combination from a point removed from the operators position and thereafter gain unauthorized access to the closure secured by the lock.

Heretofore, various means have been provided to be used in connection with conventional combination lock dials, which shield the greater portion of the dial from view by unauthorized persons. These have generally taken the form of a shield or cover provided with a window exposing only a limited number or" the dial markings vto view along an axis perpendicular to the face of the dial. Such dial shields have the dual purpose of hampering observation of the dial numbers by persons to either side of the operator while the operator is dialing the combination, and limiting the range of exposed dial markings which are visible so that the body of the operator will shield the exposed dial area from observation by persons at remote locations to the rear of the operator. These dial shields, however, are usually in the form of additional accessories which must be associated with the combination lock and dial, and in many cases afford such a limited visible dial area that the lock dial must be operated very slowly in order to bring the proper numbers on the dial into registry with the index mark. Also, because of the restricted visible dial area, the numbers are often so obscured or diicult to count that the operator must make a number of attempts before the successful combination is dialed.

Another disadvantage of circular dial type combination locks, whether they are provided with dial shields or not,

is that the dial and dial ring are uniformly formed of opaque material, so that the area of the safe or file cabinet wall immediately behind the dial and dial ring is not visible. It is not an uncommon practice for persons who are seeking unauthorized admission to the safe or ile cabinet to open the lock by drilling a hole through the dial, the dial ring and the safe or iile cabinet wall, into the lock housing, at a point such that an instrument can be inserted into the lock housing to retract the bolt. In such instances, if the person then replaces the drilled opaque dial with an identical dial, it is not apparent thereafter that the lock has been tampered with.

An object of the present invention, therefore, is the provision of a novel dial and dial ring assembly for combination locks, which effectively prevents unauthorized viewing of the dial markings as they are moved into registration with the index mark, without materially irn- 2,836,052 Patented May 27, 1958 pairing or interfering with the operators vision of the markings.

Another object of the present invention is the provision of a novel dial assembly for combination locks constructed in such a manner that the surface area on which the dial assembly is supported Vis visible through the dial, thereby discouraging unauthorized actuation of the lock by drilling through the dial supporting body.

Another object of the present invention is the novel construction of a dial assembly for combination locks, in which visibility of the dial markings to persons other than the operator is severely restricted and any apertures drilled through the dial supporting body to gain unauthorized admission tothe lock are exposed to view.

Other objects, advantages and capabilities of the present invention will become apparent from the following detail description, taken in conjunction with the accompanying drawings, wherein only a preferred embodiment of the invention is illustrated.

In the drawing:

Figure l is a front elevation of a dial assembly for combination locks .embodying the present invention, illustrated on a fragmentary portion of a safe door;

Figure 2 is a vertical transverse section view along the lines 2-2 of Figure l;

Figure 3 is atop plan View of the dial assembly; and

Figure 4 is a perspective of the annular shield insert employed in one embodiment of the present invention.

Referring to the drawing wherein like reference characters designate corresponding parts throughout the several iigures, the combination lock dial assembly, designated generally by the reference character 19, is adapted to be mounted in the conventional manner on a closure panel 11 such as a safe door, a file cabinet drawer wall, or the like, and to be secured to the lock actuating spindle 12 projecting forwardly of the closure panel through a suitable aperture 13 therein from a combination lock casing 145 mounted `on the inner surface of the closure panel. The combination lock casing 14 and the lock components may be of any conventional construction, such as that disclosed in my earlier United States Patent No. 2,575,674, granted November 20, 1951.

The dial assembly 10 includes a circular dial 15 of Lucite or other transparent piastic material having a planar rear surface 16, a peripheral surface 17 of sufficient width to accommodate dial markings or other indicia thereon, and a front surface 13 in the form of a conical annulus extending from a maximum spacing relative to the rear surface 16 at the periphery of the dial to a minimum spacing at its inner end. At the inner end of the annular front surface l is an annular shoulder portion 19 supporting a dial knob 20 of truncated conical form, which may be of plastic material molded or milled integral with or separate from the dial 15', or a metallic knob afxed to the dial 15. The knob 2G is provided with an axial cylindrical bore aligned with an aperture 21 in the dial l5 to be tted upon the end of the lock spindle 12 for imparting rotation to the spindle 12.

A dial ring 22 is assembled with the dial 15, and in accordance with conventional practice, is in the general form of a circular body of greater diameter than the dial 1S having a disc-shaped backing portion Z3 adapted to be secured to the closure panel 11 between the panel and the dial 15 and an annular flange portion 24 forming an encasing surround for the periphery of the dial 15 and projecting outwardly beyond the front surface 18 of the dial. The annular iiange portion 24 of the dial ring 22 is of substantially right triangular cross-section having a cylindrical inwardly disposed wall 25 concentric with and spaced slightly from the periphery 17 of the dial 15, an annular front surface 26 at right anglesv theretaken i l inclined at large angles to Y to and an outer surface of revolution 27 inclined .rearwardly from the surface 26 and outwardly h'om the axis Y of the dial ring. The dial ring 22 is preferably formed from one'otfthemethyl methaciylateor polystyrene resins such as 'Lucite, Plexiglas,'andY the. like, by millingor Y molding the same into'the desired shape.V i" t An opaquesplit ring shield member '28 is'adaptedf to be 'inserted between the periphery V17 of Ythe dial 15 vand the inner wall 25 of the dial ring`22 and .resilient'l'y heldY against the wall 25 in surroundingY relation to the dial periphery 17. Thisrshield member 28 is constructed'ot' While but one preferred embodiment ofthe invention has been particularly shownand described, it is apparent Y that various modifications may be'made without departing from the spirit and scope of the invention, and it is desired, therefore, that only such limitations shall'be placed thereon as are set forth in theappended claims. I claim: Y i

l. In a dial assembly for permutation flocks, a rotat-V V able circular dial having a cylindrical peripheryVV and dial sheet metal deformed .intoan annulus of greater diameter Y than that of the dial'ringwall 25 and compresses a band of the width of theinner wall 25. ofthe dial ring 22 over Vthe'major portion of. its length having'arrelieved area 29 formrngasight opening disposed intermediate'the ends of the shield member 28.V The relieved area is .handled Y Y along one edge of the shield member 28 by aconnecting strip 35) having a pointer formation 31 intermediate the shoulders 32. laterallybounding the relieved area 29 and narrowed sections 33 extending from thepointer 31 substantially half way to the shoulders 32 forming' resilient arms to facilitate manual SXDg of the'split ringlshield member. 1 Thei shield member sprung to assumea diameter'slightly smaller than that of the inner wall 25 of the dial ring 2Zfso that the shield may be inserted into the dial`ring and released to assume a'positionj against the inner dial ring wall 25 and'fric- Y tionally maintained in such position byV the sprung condition of the shield member 28.

2S is` Vdesigned* to Ybe manuallyYV If desired, the shield memberZS may be dispensed with byV merely frostin Vthe inner wall 25 of the dialring 22 in a pattern rendering the dial ring 22 translucent only over the region that would otherwise have ,been shielded by the shielding member 28.

The-dial graduations or markings, indicated at are the like, into the periph-Y incised as by etching, milling, or ery 17 of the dial 15 and are then filled with stickipaint or like opaque material. a paint of a color which blends with the color of the dial 15 is iirst applied tothe surfaces of the incised dial Ymarkings 34, and this blending color is then overlaidV with a paint of a contrasting color. In this way, the dial markings facing observation points exterior to the Ydial are rendered readily visible, while the dial markings on the opposite portion ofthe dial peripheryare rendered substantially indistinguishable.

By the construction herein described,tthe dial markings 34 on the periphery 17 ofthe dial 15 are visible' through only a very limited sector above the dial 15 when the dial assembly is mounted on a closure panel. .The limited range of visibility transversely of the closure Vpanel preyents detection of thedial markings by persons stationed r to the side of the operator during manipulation of the dial by an' authorized person.V Further, theV dial ring flange 24 provides a lightrefracting body disposed relative to the dialmarkings to pass only those light raysre ected from theidial markings which emerge from the ring along axes'inclined at small angles to the plane of the dial 15 and distort o`r internally reflect light rays the dial 15 in excess Vof fty or sixty degrees.V The optical characteristics of the dial ring'ZS, therefore, so restrict the angles of emergence of light rays as to render thedial markings visible only from positions directly above and extending only a few feet outwardly fromr the closure panel. substantially withpthat occupied by the head of an operator vwhen the operator'stands at.the usual position of address to the'dialQthepositions to the operator from which the combination being dialed in`this manner.

In the preferred embodiment,

YAs this area concides y the side of or behind Vsegment of said'ang'e.

Vforward edge of said periphery,

face of revolution and Vforming markings on said periphery, acircular dialring of transparent material adapted to be'xed to a supporting surface in coaxial underlying relation tossaid dial and having an uninterrupted annular peripheraly flange projecting in encircling concentric slightlyfspaced relation with the.V

' through only a limited arcuate segment of saidange,

`2. In a dialtassembly Vfor permutation locks,=a rotar-jk able circular dial having a cylindrical periphery and dial markings onsaid periphery, a circular dial lring of trans parent material adapted to be fixed to a supporting sur-Y face and coaxially mounted relative to said dial in under-Y Y lying relation therewith, said dial ring terminating peripherally in an uninterrupted annular flange projecting in encircling concentric relation with the periphery of said dial, said annular ange having an inner cylindrical surface conformingrclosely to the periphery of said dial, an outer surface spaced radially outwardly of said inner` Vsur,

i face, and a planar annular surface lying in "a plane sub stantially normal' to said inner cylindrical Vsurface and spaced forwardly from said dial periphery interconnect.- ing said outer and inner surfaces atttheforward edges 'thereof'to internally reilect the Yimage-forming rays ema@ dial markings along axeslinclined atv nating from said large angles to the plane of said -dialfor limiting trans.-

mission of distinguishable images Aof said dial markingsto a small anglesphericalfsector extending about the.

of said dial, andl shield means rendering said an'ge non-.`

transparent to Vsaid dial markings over the-major portion of said dial periphery and providing a sight area through' which'said dial markings'are visible over a limited arcuate 3.V In a dial assembly for permutation locks, a rotatable circular dialoftransparent materiallhaving a cylindricalV periphery and Y dial vmarkings immediately .adjacent the transparent material coaxially Ymounted, relative to said Vdial having avbase adapted to be lfixed to avsupporting surface and interposed between said dial and said surface and an uninterrupted annv ar Aperipheral flange integral with said base projecting forwardly from said base in encircling concentric relation wrth the periphery of `said dial, said angerhaving antinner cylindricalsurface con-A forming substantially tothe diameter of said dial, an outer surface of revolution concentric with said .inner Y therefrom,and a planar annular surface lying .in a planernormal to said inner cylindrical surfaceand spaced forwardly from the front edge of said'dial periphery interconnecting the for.

ward edges of said inner cylindrical surface and said surface for image-forming rays propagated alongV Y axis of said dial to conne emergent distinguishableimages fromV said dial markings of said dial markingsto the space between the rearrnosti n and a Ycone ofY revolution about thei axis ofnsaid dial whose elements form small angles with plane of 'said dial a circulardia'l Vring ofV an internalretlecting surj axes subtending small angles with the said 'rearmost plane, and shielding means forshieldin'gY said dial markings against observation through said ange over the portions of said flange complementary to a limited arcuate segment thereof.

4. The combination recited in claim 2, wherein said circular dial and said circular dial ring and dial ring ange are constructed of Lucite.

5. In a dial assembly for permutation locks, a circular dial having a cylindrical periphery and dial markings on said periphery, a circular dial ring of transparent material adapted to be fixed on a supported surface and having a disc portion and an integral, uninterrupted peripheral llange portion projecting from said disc portion and dening therewith a forwardly opening cylindrical bore of greater depth than the width of said dial periphery encircled by said ange portion, said dial being rotatably disposed in said bore in concentric relation to said ange with said dial periphery wholly underlying said ange, and said peripheral ange portion terminating forwardly in a planar, annular surface lying substantially normal to the plane of said cylindrical periphery and spaced forwardly therefrom, a removable shielding member comprising a split annular band of sheet metal of a width band may be sprung to a reduced diameter for insertion between said ange and dial periphery and resiliently retained against said ange in tensioned condition.

References Cited in the le of this patent UNITED STATES PATENTS D.l7l,1l7 Ball Dec. 22, 1953 1,435,992 Strauss et al Nov. 2l, 1922 2,248,758 Higonnet et al. July 8, 1941 2,673,545 Insul Mar. 30, 1954 2,690,664 Miller Oct. 5, 1954 2,728,215 Bremer Dec. 27, 1955 

